Ensure locations are always provided, but don't store them yet.

pkg/front_end/lib/src/fasta/builder/formal_parameter_builder.dart

Index: pkg/front_end/lib/src/fasta/builder/formal_parameter_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/builder/formal_parameter_builder.dart b/pkg/front_end/lib/src/fasta/builder/formal_parameter_builder.dart
index 73ca5fe3eca0e7d4ce68b06e331de10c32ae1905..fbe939f641b6097340c9a718c59a5c941d7eeeeb 100644
--- a/pkg/front_end/lib/src/fasta/builder/formal_parameter_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/formal_parameter_builder.dart
@@ -8,6 +8,7 @@ import 'package:front_end/src/fasta/parser/parser.dart' show
     FormalParameterType;
 
 import 'builder.dart' show
+    LibraryBuilder,
     MetadataBuilder,
     ModifierBuilder,
     TypeBuilder;
@@ -28,7 +29,8 @@ abstract class FormalParameterBuilder<T extends TypeBuilder>
   FormalParameterType kind = FormalParameterType.REQUIRED;
 
   FormalParameterBuilder(this.metadata, this.modifiers, this.type, this.name,
-      this.hasThis);
+      this.hasThis, LibraryBuilder compilationUnit, int charOffset)
+      : super(compilationUnit, charOffset);
 
   bool get isRequired => kind.isRequired;